1. Field of the Invention
The present invention relates to a device for connecting and retaining an electric cord, and in particular to a device that realizes electric connection with an electric cord without additional tools/jigs and that is applicable to bulb sockets and electric controllers.
2. The Related Arts
Lighting strings are widely used in various celebrations/holidays and events/festivals/meetings, where the lighting strings are for example hung on trees or building or even transportation vehicles to enhance pleasure atmosphere by the lighting effect provided by the lighting strings.
A lighting string comprises a plurality of light bulbs or lighting elements, which each connected with an electric cord to receive electric power from an external source for lighting. The conventional ways of connecting the light bulb to the electric cord has the following general disadvantages:
(1) The bulb is directly fixed to the cord, often in a serial connection, so that when one of the bulbs of a lighting string is broken, the bulbs that are located behinds the broken bulb cannot receive electric power and cannot be lit; and in addition mounting and removing the bulb to/from the cord is difficult.
(2) The distance between adjacent bulbs is fixed and there is no way that a user may adjust the distance by himself or herself to suit for different applications.
Another known way of connecting a bulb to an electric cord is first using a jig or tool to mount a bulb socket to the electric cord and form electric connection between terminals of the socket and the cord. This known way is of the advantages of easy and efficient manufacturing and assembling, but still suffers some disadvantages:
(1) Mounting the bulb socket to the cord requires jigs/tools operated by experienced workers so that manufacturing is subjected to the limitation of site and experienced operators, thereby being less flexible in manufacturing.
(2) The bulb socket, once mounted to the electric cord, cannot be easily dismounted or dismounting may easily cause damage to the lighting string or the cord, leading to failure of operation of the lighting string.
(3) The distance between adjacent sockets is usually set fixed and a user is not allowed adjust the distance by himself/herself so that the lighting string with such bulb sockets cannot suit for different applications.
On the other hand, the lighting string is only lit in the nighttime or during the period of festivals and is not continuously lit for 24 hours a day. Thus, a controller is often employed to control the lighting of the lighting string. The controller connects the lighting string to an external power source. The controller, although operable in timely controlling lighting of the lighting string, has drawbacks:
(1) Assembling of the controller and connection of the controller with electric cords are carried out by experienced workers and special tools/jigs may be needed, both making the manufacturing time- and labor-consuming.
(2) The controller includes a circuit board carrying control circuits and the circuit board is connected to electric cords/wires by soldering, which, once again, making the manufacturing very time-consuming and reducing the passing rate of product.